According to recent spread of self-medication, equipment for measuring blood pressure at home is quickly being diffused in general home.
Blood pressure monitors for home use, which are being diffused now, have a function for displaying blood pressure levels with large diffusion at different times as measured values, or a function for sounding a buzzer to inform patients of a degree of risk when a value at one-time measurement exceeds a certain value. Further, for example, a patent document 1 (Japanese Patent Application Laid-Open No. 11-33003 (1999)) discloses a blood pressure monitor for measuring blood pressure from normal time via a constant moving load to return to normal state and analyzing ventricular function of patients.
The blood pressure is a barometer of analysis, and it is effective for preventing of cardiovascular diseases such as cerebral apoplexy, cardiac failure and myocardial infarct to analyze the risk based on the blood pressure.
For example, in a document other than the Patent Document 1 (Kario Nanaomi, “Risk of early-morning high blood pressure and cerebrovascular disease” “Journal of Blood Pressure” November”, Sentan Igaku-sha, Nov. 1, 2002, vol. 9, no. 11, p. 94–97), the inventors of this application refer to relation between abrupt rise in blood pressure and the cerebral apoplexy which is their studied result. Such abrupt rise in the blood pressure is called as morning surge and occurs one to one and half hour after uprising. Further, the inventors describe necessity of obtaining interrelation of a change in blood pressure when the risk of cardiovascular diseases is analyzed.
The blood pressure has intra-day fluctuating rhythm such that the blood pressure changes due to individual physical activity, reaction to a stress, reaction of cardiovascular system to behavior pattern and the like, the blood pressure drops at night time but rises before and after awakening in the morning. Prior blood pressure monitors, however, display a fluctuation of the blood pressure simply along a time base or represent a grade of the fluctuation only with numerical values statistically.
The prior blood pressure monitors disclosed in Patent Document 1, however, have a problem such that it is not provided with a following function. The function is for synthetically analyzing and evaluating information about a blood pressure measured value which changes with age according to a blood pressure value and aged deterioration of variability. Further, the function is for estimating individual cardiovascular risk so as to inform patients or doctors of the estimated cardiovascular risk as information which is used for blood pressure management cure.